Sciencemadness Discussion Board

reduced by copper

j4yman - 24-5-2006 at 04:43

The question simply is, which could be reduced by Cu?
Sn2+ (superscript 2+)
Ag+ (superscript +)
Zn2+ (superscript 2+)

How do i figure this out? ...by using some sort of database?
I know copper will spontaneously reduce Ag+
Not sure about the other 2.


The other question :)
Consider the following reduction potentials:
Cu2+ + 2e- --> Cu E° = +0.34 V
Pb2+ + 2e- --> Pb E° = -0.13
For a galvanic cell employing the Cu, Cu2+, Pb, Pb2+ couples, calculate the maximum amount of work (in kJ) that would accompany the reaction of one mole of lead under standard conditions.
________kJ ?

12AX7 - 24-5-2006 at 05:46

Ya, look up a table of reduction potentials.

As for the other, that's easy, find the biggest difference (Cu2+ + Pb > Pb2+ + Cu = 0.34 + 0.13 = 0.47V) and calculate the energy two electrons per atom get. An electron through 1V gains 1eV energy, and there's 6.02 x 10^23 atoms per mole and two electrons exchanged per ion ("2+") and there's 6.25 x 10^21 electrons in one kilocoulomb and C * V = J so you just have to put it together and crank unit conversion to get kJ/mol.

I never liked kJ/mol or any of that crap. eV own.

Tim

Darkblade48 - 24-5-2006 at 05:51

Check out a table of reducing potentials, or alternatively, check out a reactivity series table.

I noticed you posted this in another forum (on a different site) as well ;)

j4yman - 24-5-2006 at 22:55

Quote:
Originally posted by 12AX7
Ya, look up a table of reduction potentials.

As for the other, that's easy, find the biggest difference (Cu2+ + Pb > Pb2+ + Cu = 0.34 + 0.13 = 0.47V) and calculate the energy two electrons per atom get. An electron through 1V gains 1eV energy, and there's 6.02 x 10^23 atoms per mole and two electrons exchanged per ion ("2+") and there's 6.25 x 10^21 electrons in one kilocoulomb and C * V = J so you just have to put it together and crank unit conversion to get kJ/mol.

I never liked kJ/mol or any of that crap. eV own.

Tim


I'm having trouble understanding this. So is V (0.47/2)?
What about C...?

j4yman - 25-5-2006 at 19:29

i got -90.7 kJ
hmmm i used Wmax = -qE
W = -(2 x 96485) x (0.47)
= -90.7 kJ